Animal fleas will have a go at anything warm blooded - if it's the wrong species they will take a few bites (presumably to compensate) so if you are getting a group of bites in one spot, it's most likely the cat.
I sometimes get a bad reaction to insect bites - it swells up and reddens a heck of a lot and is much worse if scratched. I cover the bite with a plaster to remind myself not to scratch, and prevent it rubbing against my clothes. I take allergy tablets or antihistamine to reduce the swelling, and often use lavender or tea tree oil on the bite too.